A seething O.J. Simpson is insisting his claim he fought off a berserk gunman is true – and says skeptics who don’t believe him are just plain nuts.

“How can a rational person think that you’d make up a story like this?” Simpson tells the TV show “Hard Copy.”

“Well, I don’t care if they believe me or not!”

The disgraced grid great told cops he tangled with a pistol-packing robber who tried to hold him up at a Los Angeles golf course last Tuesday.

Simpson said he scared off his assailant by sinking his teeth into the man’s hand.

But some believe Simpson made up the story lock, stock and barrel, simply as a way to drum up sympathy – and free publicity – for himself.

O.J. says a lot of folks are still so furious he beat a murder rap in the grisly 1994 butcher-knife slayings of his ex-wife Nicole Brown Simpson and her pal Ron Goldman that they wished the gunman had blown him away.

“People who are anti-me say, ‘Oh, I wish the guy would have shot him or something,'” he says.

Simpson also says he’s disgusted by media reports of his alleged confrontation because “there’s a certain sarcasm with some of these, I’ve noticed.”

While O.J. said he got part of his attacker’s license plate number, cops couldn’t find a match.

“They asked me if I wore glasses. They kind of inquired that maybe I got one of the letters wrong or something,” he complains in the interview, airing today at 1 p.m. on Channel 11.

Simpson says he’s not given enough protection by cops, and that one man who once stalked him with a gun was let off with probation.

Simpson says that when he was accosted last week, “I grabbed [the gun] and I pushed it down. I didn’t want the barrel pointing at me.

“I was telling him to get the heck out of here. ‘What are you doing? You’re going to screw up your life. Trust me, man, this is not the kind of crap you want to do.'”